1. FIELD OF THE INVENTION
The present invention relates generally to the transportable container industry and the problem within that industry of reliably monitoring large numbers of refrigerated or otherwise environmentally controlled containers which throughout the world are used to ship perishable commodities. The invention, more particularly, involves a computer controlled monitoring system which provides for, among other things, continuous data gathering operation with respect to all controlled containers adapted to the system, alarm and other capabilities such as diagnostics, and automated centralized monitoring and control and particular container storage sites, e.g. on board a container vessel or at a land based storage terminal.
2. DESCRIPTION OF THE PRIOR ART
In recent years the shipping industry has undergone dramatic changes because of the introduction of containerized cargo. Instead of handling cargo individually in all its myriad forms and shapes, cargo is now increasingly shipped in large standarized containers which can quickly and easily be loaded and unloaded, or otherwise moved, using standardized handling equipment. Because of their standard size and shape, such containers can also be stored compactly in large numbers under known and more controllable space requirements. In use, a transportable container will generally carry the shipped goods from their point of origin to their destination, such that in transporting the cargo only the uniform sized container will ever be handled.
To provide the special environmental conditions required for shipping perishable commodities, shippers will use transportable refrigerated containers, called "reefers". However, while widespread use of reefers has greatly improved shipping efficiencies, the problem of shipping perishables without spoilage persists because the reefers often fail to adequately maintain their temperature environments. The source of any temperature problem will vary and may go totally undetected: It might be a power failure at a land based terminal or on a container ship, or it might be a problem in the reefer's refrigeration unit, or some other malfunction in the reefer's cooling which causes the reefer temperature to wander outside of prescribed limits. To minimize losses, it is desirable to monitor the reefers during transit so that malfunctions can be detected and the problems corrected before cargos are lost. Heretofore, however, monitoring equipment and methods have been inefficient and unreliable. For example, it is not uncommon to have a terminal site employee or a member of a vessel's crew periodically walk through the storage yard or on deck and take readings from individual reefer temperature gauges. Strip chart recorders, and the like, have also been used, and in some storage locations temperature transducers are hardwired from numerous stored reefers to a single monitoring location. Such conventional techniques, beside being very inefficient when handling large numbers of containers constantly being moved about, depend on the human observer and, as a result, are highly vulnerable to human error and inattention; they provide no warning of a container malfunction until an out of limit condition actually occurs and is noticed. Conventional monitoring techniques also make it difficult to obtain an accurate and complete history of the reefer's operation during transit through many storage locations and usually require the rewiring of a vessel, a costly project which takes the vessel out of service for the time needed to rewire.
The present invention substantially overcomes the above-mentioned problems by providing an efficient and reliable computer controlled monitoring system wherein, among other things, all reefer parameter data suitably representative of a reefer's operating condition are continuously and automatically monitored so as to provide a readily retrievable history of the reefer's operation. In accordance with the invention, reefers adapted to the system when stored at a properly equipped storage site and plugged into the site's power source will automatically be connected into a central monitoring computer which is adapted to automatically poll all of the on-site containers as to their condition. Such a storage site could be a land based terminal, or on board a vessel or other transporting vehicle. The system also provides for automatically identifying and keeping track of all containers being connected to or disconnected from the power source in a storage area, and can be set to trigger any combination of local and remote alarms under any prescribed set of alarm conditions. The present invention substantially reduces human error and oversight problems and dramatically reduces the tracking and recordkeeping problems produced by large numbers of refrigerated containers being placed in the stream of commerce.